Process for converting oil



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I l Oct 11, w. M. CROSS PROCESS FOR CONVERTING OIL Fil8d Ablll 1923 Patented Oct. 11, 1927.

UNITED STATES PATENT OFFICE.

WALTER M. CROSS, OF KANSAS CITY, MISSOURI, ASSIGNOR TO GASOLINE PRODUCTS COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS FOR CONVERTING 01L.

Application filed April 3, 1923. Serial No. 629,723.

This invention relates to improvements in a process for converting oils, and refers more particularly to a process for the pressure conversion of oils while maintaining them substantially in the liquid phase and subsequently releasing the pressure to relieve the oils by distillation of their lighter fractions. Among the salient objects of the invention are to provide a process in which oils are heated to a conversion temperature and maintained during the conversion of the oil at pressures sufiicient to prevent any appreciable vaporization or to maintain the oil substantially in the liquid phase during the conversion reaction; to provide a process in which subsequent to conversion under these conditions, the pressure is released whereby an active distillation is effected and the vaporous fractions removed during this distillation fractionally condensed, the unvaporized portions either diverted'from the process -or recycled; to provide 'a process whereby oils may be effectively changed from relatively high boiling point to low boiling point oils having the characteristics of gasoline in a single process; and a process by means of which relatively heavy oils such as fuel oil and other hydrocarbons having a heavy carbon content may be efi'ectively treated, and to provide an apparatus for carrying out this process.

The single figure is a diagrammatic side elevational view of the apparatus.

By referring to the drawing the oil to be treated which may consist of a charging stocksuch as gas oil, fuel oil or numerous other oils which are used as charging stock for producing light hydrocarbons, is introduced through the line 1 and charged through pumps2 and 3 into the upper preheating tubes 4 of the heating system. The pump 2 is a low pressure pump and 3 a high pressure pump by means of which the charging stockis introduced to the'system. Two pumps are used due to the high pressure maintained in the heating system, and also to facilitate the operation of certain recycled products, as will be hereinafter explained. The oil charged to the preheating tubes .4 is circulated downwardly in the upper or preheating portion of the furnace 5. From the lower tube of the coil 4 the oilpasses through a transfer line 6 to the lowest tube or bank of tubes in the main heat-i coil 7 5 positioned in the hottest portionS of the farnace- 9. Thefurnace is preferably heated by means of gas burners not shown. Open brick work walls divide the separate portlons of the furnace.

The oil after passing through the coil 7 .has been sufficiently heated to raise the temperature of' the oil to a conversion state. In this condition it is transferred to the conversion chamber 10 which consists of an elongated insulated chamber wherein the oil is maintained in a substantial body while the conversion takes place.

The heating and conversion stages are maintained during operation at pressure 'sufficient to prevent any substantial vaporization o fthe oil during treatment, that is, a

gaseous pressure is maintained upon the oil in the conversion stage suflicient to maintain the oil in substantially a liquid phase whereby the conversion or molecular rearrangement of the oil is carried on while the oil is substantially in a liquid condition.

The chamber is equipped with a drawoff line 11 controlled by a valve 12 for removmg, if desired, any heavy viscous residual material which may collect and accumulate due to the conversion which takes place in this stage of operation.

The liquid oil after passing through the conversion chamber 10 is directed through a line 13 to a vaporizing still or column 14 where it is introduced at a reduced pressure or under substantially atmospheric conditions, the pressure on the oil being relieved by the valve 15 interposed in the connecting line 13. This still or column may be heavily insulated to prevent loss of heat by radiation and has a perforated line 16 arranged in the lower portion thereof for the introduction of superheated steam or other heat modifying agent. This steam line may or may not be used according to the conditions necessary to be created in the still to produce the desired reaction or vaporization of the oil introduced from the conversion chamber. Normally the relieving of the pressure upon the oil by the. valve 15 will cause the vaporization of a greater part of the lighter fractions contained 'in the synthetic crude or oil converted in the liquid phase in the chamber 10. The fractions relieved from the oil with the reduction of pressure-will rise into the top of the still 14 and pass ofi through the line 17 controlled by a valve 18 to a second fractional condensing column 19. Certain of the higher boiling point fractions will be separated in the still 14 due to the positioning of refluxing pans 20 which serve as obstructions to the passage of the vapors. The unvaporized products will drop into the bottom of the still where they may be drawn oil through the line 21 and collected in a storage tank not shown. The liquid level in the bottom of the still is maintained by a mechanism shown at 22 which comprises a pivoted ball float 23 having a lever 24 connected by a rod 25 to a lever on the valve 26. A liquid line 27 and an equalizing vapor pipe 28 communicate with the liquid level control mechanism, thus there is constantly maintained a liquid level at a known height in the vaporizing oil.

The vapors passing over through the line 17 are introduced to the fractionating column and rise therethrough being subjected to a cooler refluxing medium, which may beintroduced by means of a spray pipe 29 or any other convenient means.

this liquid cooling medium and after fl assing through a circuitous travel due to the positioning of additional bafile members or pans 30 in the upper part of the column, the vapors pass off through the line .31 controlled by a valve 32 to a water condensing coil 33 positioned in the condenser box 34 where final condensation takes place. The discharge end of the condenser coil is connected by a pipe '35 regulated by a valve 36 to a gas separator 37. Here the gases and liquid are separated, the former passing off through a pipe 38 controlled by a valve 39 and returned to the burners of the furnace for consumption while the liquid distillate is drawn off through the valve 40 to storage not shown.

In a similar manner to that shown in connection with the vaporizing still a liquid level is also maintained in the fractional condensing column by means of a mechanism identical to that explained at 22 and designated in the drawing as 41. This mechanism controls the valve 42 interposed in the drawoff line 43 so that the liquid reflux condensate and the recycled cooling medium are drawn oil at a controlled rate through the pipe 43 which has connections 44 and 45 controlled by valves 46 and 47 respectively. By directing the oil through the pipe 44 it is sent to storage and if diverted through the pipe 45 it is recycled with a charging stock through the line 1 either to the heat ng coil or a portion with the charging stock through the line 48 controlled by a valve 49 into the top of the fractionatlng column by means of a spray 29.

By maintaining a liquid levelin a vaporizing still and fractional corqiensing column there is kept a constant seal upon these After being subjected to the refluxing action of chambers which prevents the vapors from being diverted and blown out through the bottoms of the column, thus interfering with the suction on the pump and causing difliculties in the operation of the process.

In operation the oil, as explained, is

charged through the pumps 2 and 3 and.

heated in the coils 4 and 7 to a conversion temperature, thence passed and accumulated in a substantial body in the chamber 10. Temperatures in the heating and conversion stages will normally range from 600 to 1000 F., while the pressure on these stages Willrange between 400 to 1000 pounds per square inch. The converted oil or synthetic crude passes from the conversion chamber at temperatures of approximately 720 F. more or less, where the pressure is reduced by the valve 15 to substantially atmospheric conditions. The pressures at most in the still will not exceed from 5 to 15 pounds. With the release of pressure there will be an immediate evolution of low boiling point fractions which may or may not be assisted by the use of superheated steam, as explained. The temperature of the vapors passing over from the top of the still through the line 17 will range from 500 F., and upwards. The liquid drawn off from the bottom of the still will be of a relatively heavy gravit such as commercial fuel oil. From the ractional condensing column the liquid recovered will have substantially the characteristics of gas oil, the temperature at the top of the column being controlled near the end point desired for the recovered distillate. This temperature may be regulated more or less by the amount of liquid refluxing medium introduced to the fractional condensing column through the pipe 48.

By means of this process anda paratus a relatively heavy 'oil may be treated so that partial cracking or conversion takes place while the oil is maintained in a substantially liquid phase in the conversion chamber and subsequently distilled under substantially atmospheric conditions, thereby relieving the converted oil of its light cracked products without the necessity of redistillation, although the products may be redistilled ifdesired for further refining or as part of a subsequent treatment for purification.

The process permits the conversion of relatively heavy oil such as. fuel oil, as the amount of carbon deposited during the initial conversion in the liquid hase is relatively limited and carbon pro uced by subsequent distillation is flushed out with the unvaporized liquid oil constituents.

I claim as my invention:

A process for converting oil comprising raising the oil to a crackin temperature in a heating stage, passing the oil to a con version stage and there maintaining it under suflicient pressure imposed by the generated vapors during reaction to maintain the oil in substantially the liquid phase, relieving the pressure on the oil and passing it through a vaporizing stage and there separating the liquid and vaporous oil constituents, subjecting the vapors evolved to afraotional condenslng action and returning selected portions of the condensate to the heating stage and to the fractional condensing stage with the charging stock, and main taining a regulated liquid level in the vaporizing and fractional condensing stages.

WALTER M. CRQSS. 

